First pass radionuclide angiography following bolus administration has been used principally for the detection and quantitation of intracardiac shunts, evaluation of right and left ventricular ejection fraction, measurement of cardiac output and various other cardiac parameters. This technique has proved its potential for non-invasive evaluation of a variety of congenital and acquired cardiovascular disorders, especially in children. A radionuclide of short half-life must be used, and the one in use to the largest extent at present is technetium-99m, which is used mainly as sodium pertechnetate with a .gamma. of 140 keV, with a physical half-life of 6 hours. There have also been proposed generator systems of Cd-109.fwdarw.Ag-109m and Os-191.fwdarw.Ir-191m. In the case of the Cd/Ag generator the half life of 1.26 years of Cd poses a problem should breakthrough occur. There has been developed a rubidium-81 krypton-81m generator with Rb half-life of 4.7 hours and Krypton half-life of 13.1 seconds. Krypton-81m is well suited for long studies but is not suitable for angiocardiography as it is readily eliminated by the lungs.
Another ultra-short lived generator is Ba-137m with a half-life of 2.55 minutes. However, its photon energy of 662 keV is too high for use with gamm cameras of the Anger type. Yet another generator is the Hg-195.fwdarw.A-195m generator, the daughter having a 30.5 seconds half-life, with the parent having a 40 hour half-life.